Many different commercial activities employ one or more explosive, pyrotechnic and gas-producing substances (herein, “explosive substances”) to achieve a variety of engineering and ultimately commercial objectives. For example, explosive substances are used in the oil and natural gas industries to enhance production in wells. Once a promising location has been identified, and the necessary rights secured, the creation of such wells typically begin with drilling a borehole into the ground to reach sought-after deposits of oil and/or natural gas. To prevent collapse of the borehole, a casing is often co-axially inserted into the borehole. In most situations, cement is pumped into a more or less annular space between the cylindrical casing and the larger cylindrical borehole wall to mechanically stabilize the well. While this method improves mechanical stabilization of the well, unfortunately, it also isolates inner portions of the casing, (i.e., the wellbore), from the sought-after deposits of oil and/or natural gas.
A perforating gun system employing explosive components is typically lowered into the casing in the borehole via a wireline or tubing conveyed. The wireline is often unrolled from a motorized spool attached to pulleys and a wireline-truck on the surface (surface truck) adapted to this purpose. In other circumstances, derricks, slips and other similar systems take the place of the surface truck. These provide an operator with an ability to raise and lower the perforating gun system inside the well. The wireline cable provides both a physical connection and an electrical connection between the equipment on the surface and the perforating gun system. The purpose of the perforating gun system is to create perforations in the casing, cement, borehole wall and, to some degree, adjacent geologic formations, to enable oil and/or natural gas to flow into the casing. Selective perforating gun systems often include more than one perforating gun, physically and electrically connected with each other in one tool string, which is then connected to the wireline. Generally, the tool string is conveyed a considerable distance from the surface depending on the depth of the well and the position of the intervals that are intended to be perforated.
Each perforating gun typically includes multiple explosive charges, such as shaped charges, that include an explosive substance, and an electrically-initiated igniter or detonator to detonate the explosive substance. An electrical signal from the wireline causes the electrically-initiated igniter or detonator to detonate the explosive substance, forcing a high energy perforating jet out of the perforation gun into a side of the casing at a high velocity, thereby perforating the casing, cement, borehole and adjacent geologic formation. Because the oil and natural gas industries have been drilling boreholes of greater depths and lengths in search of resources, the ability to detonate and perforate selectively has taken on increasing importance. The ability to more precisely apply one or a series of detonations, as well as the ability to cause detonations further away from surface equipment, makes it desirable to have better control over perforation systems inside wells.